1. Technical Field
The present invention relates to a method of manufacturing an electro-optical device, and in particular, relates to a method of manufacturing an electro-optical device that has a plurality of data lines, a plurality of scanning lines, and a plurality of driving elements on a substrate.
2. Related Art
In general, as electro-optical device that has, on an insulating substrate, a plurality of data lines and a plurality of scanning lines, a plurality of driving elements formed to correspond to intersections of the plurality of data lines and the plurality of scanning lines for individual pixels, and pixel electrodes provided to correspond to the driving elements, an active matrix driving mode liquid crystal device has been known.
When manufacturing an active matrix driving mode liquid crystal device, on the insulating substrate, a semiconductor layer or various conductive films are formed by a dry etching method or a plasma CVD (Chemical Vapor Deposition) method, and thus pixel electrodes, data lines, scanning lines, pixel switching thin film transistors (hereinafter referred to as TFTs) electrically connected to the scanning lines and the data lines, and so on are formed. In this case, an unexpected excess current may be caused by electric charges or an electrostatic charge accumulated on the surface of a substrate due to film formation by the plasma CVD method or the like. Due to the excess current, the scanning line may be damaged. In particular, a dielectric breakdown may occur between a gate of a TFT that is connected to the scanning line or is to be a part of the scanning line and a source/drain thereof.
For this reason, in Japanese Patent No. 3395598, there is disclosed a technology which, in order to prevent the occurrence of the excess current, forms short-circuit wiring lines to be electrically connected to the plurality of scanning lines, respectively, and disperses the electric charges or the electrostatic charge outside the substrate. In Japanese Patent No. 3395598, after the TFTs and so on are formed, the short-circuit wiring lines are cut, such that the scanning lines are electrically separated from one another.
A method of cutting the short-circuit wiring lines is as follows. First, when a contact hole for electrically connecting the pixel electrode and the TFT is formed in an interlayer insulating film for isolating the TFT from the pixel electrode, a short-circuit portion cutting hole that extends from the surface of the interlayer insulating film to the short-circuit wiring line is simultaneously formed. Then, after a conductive film for forming the pixel electrode is formed, when the conductive film is patterned using a photolithography method and an etching method, a short-circuit portion of the scanning line is simultaneously cut through the cutting hole.
However, in the related art, since the conductive film is formed after the cutting hole for cutting the short-circuit wiring line is formed, the conductive film is also formed at the bottom and side wall portions of the cutting hole. Further, when conductive film is patterned, a resist for forming the pixel electrode is laminated in the cutting hole. When the resist is patterned by the photolithography method, an aspect ratio of the cutting hole is made large. Accordingly, even through exposure accuracy is increased, the resist may remain in the cutting hole, and the short-circuit wiring line may be not cut. Therefore, in order to reliably cut the short-circuit wiring line, the resist and the conductive film in the cutting hole need to be completely removed. Therefore, when cutting the short-circuit wiring line, etching needs to be excessively performed in order to simultaneously remove the conductive film and the resist in the cutting hole.
A base insulating film serving as an interlayer insulating film is formed below the short-circuit wiring line, and a lower light-shielding film is formed below the base insulating film. When etching is excessively performed in the cutting hole, the base insulating film below the cutting hole may be thinned or etching may reach the lower light-shielding film. Accordingly, a crack may occur in the lower light-shielding film in the periphery of the cutting hole, and a display inconsistency may occur due to light leakage from the cracked portion. As a result, manufacturing yield of a liquid crystal device may be degraded.